Fiber reinforced composite materials particularly carbon fiber reinforced composite materials are used in aircraft construction. Conventionally thin stringers and thin skin sections made of these carbon fiber reinforced materials are used, for example in passenger aircraft of the “Airbus” (Tradename) line. Stringers and skin sections are interconnected by adhesive bonding or riveting. The skin surface areas and the stringer surface areas to be joined are not uniformly smooth or level so that joining gaps or air pockets occur. These joining gaps need not occur throughout the joined surface areas. Rather, joining gaps may occur depending on the topography of the surfaces to be joined. Thus, these joining gaps may be randomly distributed between the surfaces being joined. These joining gaps or air pockets are undesirable since they reduce the mechanical strength of the joint. To avoid joining gaps it is known to use a so-called shim mass to fill the gap or gaps. The quantity of shim mass is determined by a maximal gap dimension. However, such maximal gap dimension is not always achieved in the manufacture of the individual stringers and skin sections. As a result, it is possible to apply too much shim mass and the excess must be removed which is rather cost intensive and time consuming. Conventionally, it is difficult to determine the exact quantity of the required shim mass because the gap depth is not uniform throughout the gap area. Rather, a hill and dale topography, in a micro sense, is involved. Prior to an adhesive bonding, for example of a stringer with a skin section, the joining surface area of the skin section is smoothed out with the shim mass, then both surface areas are coated with an adhesive and pressed against each other. When the adhesive has cured, the connection or joint is permanent and provides a self-retaining material bonding.
Riveting structural components to each other also leaves room for improvement with regard to eliminating the need for a mechanical preparation of the joining surfaces of the components to be connected. Preparing the joining surfaces, for example by the fine grinding or polishing so that these surfaces are completely or at least substantially plane and do not form any gap, is cost intensive and time consuming. Thus, fine grinding and polishing of these joining surface areas should be avoided.
Furthermore, the above conventional joining methods are not suitable for connecting relatively thick walled components to each other such as skin sections and stringers made of carbon fiber reinforced composite materials. Such components are relatively rigid. The dimensions of gaps that form between or rather on the joining surfaces of rigid thick structural components depend on the manufacturing tolerances that must be accepted for economic reasons. Rigid components if pressed to each other do not allow for minimizing the gap dimensions due to their rigidity. Prior art solutions as described in European Patent Publication EP 0,089,954 B1, German Patent Publication DE 197 39 885 A1, and U.S. Pat. Nos. 4,980,005 and 5,963,660 do not provide any solutions for the above outlined problems.